聊聊artemis的ActiveMQMetricsPlugin

public interface ActiveMQMetricsPlugin extends Serializable {
​
   ActiveMQMetricsPlugin init(Map<String, String> options);
​
   MeterRegistry getRegistry();
}

public class SimpleMetricsPlugin implements ActiveMQMetricsPlugin {
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   private transient MeterRegistry meterRegistry;
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   private Map<String, String> options;
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   @Override
   public ActiveMQMetricsPlugin init(Map<String, String> options) {
      this.meterRegistry = new SimpleMeterRegistry();
      this.options = options;
      return this;
   }
​
   @Override
   public MeterRegistry getRegistry() {
      return meterRegistry;
   }
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   public Map<String, String> getOptions() {
      return options;
   }
}

public class LoggingMetricsPlugin implements ActiveMQMetricsPlugin {
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   private transient MeterRegistry meterRegistry;
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   @Override
   public ActiveMQMetricsPlugin init(Map<String, String> options) {
      this.meterRegistry = new LoggingMeterRegistry();
      return this;
   }
​
   @Override
   public MeterRegistry getRegistry() {
      return meterRegistry;
   }
}

public final class FileConfigurationParser extends XMLConfigurationUtil {
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   //......
​
   private ActiveMQMetricsPlugin parseMetricsPlugin(final Node item, final Configuration config) {
      final String clazz = item.getAttributes().getNamedItem("class-name").getNodeValue();
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      Map<String, String> properties = getMapOfChildPropertyElements(item);
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      ActiveMQMetricsPlugin metricsPlugin = AccessController.doPrivileged(new PrivilegedAction<ActiveMQMetricsPlugin>() {
         @Override
         public ActiveMQMetricsPlugin run() {
            return (ActiveMQMetricsPlugin) ClassloadingUtil.newInstanceFromClassLoader(FileConfigurationParser.class, clazz);
         }
      });
​
      ActiveMQServerLogger.LOGGER.initializingMetricsPlugin(clazz, properties.toString());
      config.setMetricsPlugin(metricsPlugin.init(properties));
​
      return metricsPlugin;
   }
​
   //......
}

public class MetricsManager {
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   private final String brokerName;
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   private final MeterRegistry meterRegistry;
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   private final Map<String, List<Meter>> meters = new ConcurrentHashMap<>();
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   public MetricsManager(String brokerName, ActiveMQMetricsPlugin metricsPlugin) {
      this.brokerName = brokerName;
      meterRegistry = metricsPlugin.getRegistry();
      Metrics.globalRegistry.add(meterRegistry);
      new JvmMemoryMetrics().bindTo(meterRegistry);
   }
​
   public MeterRegistry getMeterRegistry() {
      return meterRegistry;
   }
​
   @FunctionalInterface
   public interface MetricGaugeBuilder {
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      void register(String metricName, Object state, ToDoubleFunction f, String description);
   }
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   public void registerQueueGauge(String address, String queue, Consumer<MetricGaugeBuilder> builder) {
      final MeterRegistry meterRegistry = this.meterRegistry;
      if (meterRegistry == null) {
         return;
      }
      final List<Gauge.Builder> newMeters = new ArrayList<>();
      builder.accept((metricName, state, f, description) -> {
         Gauge.Builder meter = Gauge
            .builder("artemis." + metricName, state, f)
            .tag("broker", brokerName)
            .tag("address", address)
            .tag("queue", queue)
            .description(description);
         newMeters.add(meter);
      });
      final String resource = ResourceNames.QUEUE + queue;
      this.meters.compute(resource, (s, meters) -> {
         //the old meters are ignored on purpose
         meters = new ArrayList<>(newMeters.size());
         for (Gauge.Builder gauge : newMeters) {
            meters.add(gauge.register(meterRegistry));
         }
         return meters;
      });
   }
​
   public void registerAddressGauge(String address, Consumer<MetricGaugeBuilder> builder) {
      final MeterRegistry meterRegistry = this.meterRegistry;
      if (meterRegistry == null) {
         return;
      }
      final List<Gauge.Builder> newMeters = new ArrayList<>();
      builder.accept((metricName, state, f, description) -> {
         Gauge.Builder meter = Gauge
            .builder("artemis." + metricName, state, f)
            .tag("broker", brokerName)
            .tag("address", address)
            .description(description);
         newMeters.add(meter);
      });
      final String resource = ResourceNames.ADDRESS + address;
      this.meters.compute(resource, (s, meters) -> {
         //the old meters are ignored on purpose
         meters = new ArrayList<>(newMeters.size());
         for (Gauge.Builder gauge : newMeters) {
            meters.add(gauge.register(meterRegistry));
         }
         return meters;
      });
   }
​
   public void registerBrokerGauge(Consumer<MetricGaugeBuilder> builder) {
      final MeterRegistry meterRegistry = this.meterRegistry;
      if (meterRegistry == null) {
         return;
      }
      final List<Gauge.Builder> newMeters = new ArrayList<>();
      builder.accept((metricName, state, f, description) -> {
         Gauge.Builder meter = Gauge
            .builder("artemis." + metricName, state, f)
            .tag("broker", brokerName)
            .description(description);
         newMeters.add(meter);
      });
      final String resource = ResourceNames.BROKER + "." + brokerName;
      this.meters.compute(resource, (s, meters) -> {
         //the old meters are ignored on purpose
         meters = new ArrayList<>(newMeters.size());
         for (Gauge.Builder gauge : newMeters) {
            meters.add(gauge.register(meterRegistry));
         }
         return meters;
      });
   }
​
   public void remove(String component) {
      meters.computeIfPresent(component, (s, meters) -> {
         if (meters == null) {
            return null;
         }
         for (Meter meter : meters) {
            Meter removed = meterRegistry.remove(meter);
            if (ActiveMQServerLogger.LOGGER.isDebugEnabled()) {
               ActiveMQServerLogger.LOGGER.debug("Removed meter: " + removed.getId());
            }
         }
         return null;
      });
   }
}